Fixed a whole bunch of MyPy errors

New release of mypy picks up more.

blender_asset_tracer/trace/expanders.py

@@ -138,6 +138,8 @@ def _expand_group(block: blendfile.BlendFileBlock):
     else:
         for child in iterators.listbase(children):
             subcoll = child.get_pointer(b'collection')
+            if subcoll is None:
+                continue
             log.debug('recursing into child collection %s', subcoll.id_name)
             yield from _expand_group(subcoll)
 

blender_asset_tracer/trace/modifier_walkers.py

@@ -87,7 +87,9 @@ def _get_texture(prop_name: bytes, dblock: blendfile.BlendFileBlock, block_name:
     yield from _get_image(b'ima', tx, block_name)
 
 
-def _get_image(prop_name: bytes, dblock: blendfile.BlendFileBlock, block_name: bytes) \
+def _get_image(prop_name: bytes,
+               dblock: typing.Optional[blendfile.BlendFileBlock],
+               block_name: bytes) \
         -> typing.Iterator[result.BlockUsage]:
     """Yield block usages from an image propery.
 

blender_asset_tracer/trace/result.py

@@ -90,7 +90,7 @@ class BlockUsage:
         self.path_base_field = path_base_field
 
         # cached by __fspath__()
-        self._abspath = None  # type: pathlib.Path
+        self._abspath = None  # type: typing.Optional[pathlib.Path]
 
     @staticmethod
     def guess_block_name(block: blendfile.BlendFileBlock) -> bytes: